FIELD OF THE INVENTION
With respect to the classification of art as established in and by the United States Patent and Trademark Office, this invention is believed to be found in the general class entitled as "Expansible Chamber Devices" and more particularly "with a linkage or transmission".
Many machinery components such as process valves, louvers, or alarm devices require a servo-actuator to provide a desired degree of angular movement Some of these components, requiring servo-actuators, are mounted on machinery or located on process equipment used in a clean room atmosphere, in the food or pharmaceutical industries, and others in hazardous, or explosive environments. Each of these applications require a servo-actuator which will not contaminate the surrounding environment with pollutants, metal fragments, or sparks.
Therefore it can be seen that a servo-actuator is required to transform linear motion to rotary motion in a compact device while at the same time providing an enclosed non-contaminating unit which has an adjustable angular displacement for use with varied components.
Some of the prior art devices, which are commercially available, utilize a linear cylinder to operate a rotary shaft by means of a pinion and rack system; chain and sprockets; or cable and pulleys. U.S. Pat. No. 2,630,132 as issued to W.J. Hughes on Mar. 3, 1953 discloses a servo-actuator which provides rotary motion as a result of linear motion. The patent as issued to Hughes does not show or disclose an enclosed device which would satisfy the environmental requirements of clean rooms or Hazardous locations. The Hughes Patent also discloses a rolling diaphragm arrangement for the piston. This prior art Patent also requires a piston guiding means interior of the piston.
There is a need to provide a fully enclosed servo-actuator which has a minimum of moving parts and is economical to manufacture. There is an additional need to provide a servo-actuator which has an adjusting means for limiting the Angular Displacement of its output shaft.
It is therefore an object of this invention to provide and it does provide, a servo-actuator which is enclosed for safe operation in clean room or hazardous environments.
It is another object of this invention to provide and it does provide, a servo-actuator which has an adjustment means for controlling or limiting the angular displacement of its output shaft.
It is a further object of this invention to provide and it does provide a servo-actuator having an angular displacement great enough to operate disk or butterfly valves to a fully opened condition.
It is still another object of the invention to provide and it does provide a servo-actuator requiring little or no lubricant.
It is yet a further object of this invention to provide and it does provide an economically manufactured servo-actuator adapted to provide adjustable angular displacements up to one hundred-eighty degrees of arc.
This present invention provides a servo-actuator which is operated by a pressurized medium such as a hydraulic fluid or a gas. This servo-actuator requires little or no lubrication and has a minimum number of parts. An adjustment means is provided to limit the angular displacement of the output shaft at one or both extents.
In addition to the above summary the following disclosure is detailed to insure adequacy and aid in the understanding of this invention. This disclosure, however is not intended to cover each new and inventive concept no matter how it may later be disguised either by variations in form or additions by further improvements. For this reason, there has been chosen specific embodiments of a pressure operated servo-actuator. This servo-actuator is fully enclosed and adapted for use in clean room or hazardous environments. These specific embodiments have been chosen for the purpose of illustration and description as shown in the accompanying drawings wherein: